koro (shook yang)

Koro is a psychological disorder characterized by delusions of penis shrinkage and
retraction into the body, accompanied by panic and fear of dying. This delusion is rooted
in Chinese metaphysics and cultural practices. The disorder
is associated with the belief that unhealthy or abnormal sexual acts (such as sex with
prostitutes, masturbation, or even nocturnal emissions) disturb the yin/yang equilibrium which allegedly exists when a husband has sex
with his wife, i.e., during "normal intercourse." This disturbance of
metaphysical harmony (loss of yang) manifests itself in penis shrinkage. Yang is the vital
essence of the male and when inappropriately expelled, it is believed, the result is a
potentially fatal dose of koro.

Koro is also thought to be transmitted through food. In 1967, there was a koro epidemic
in Singapore after newspapers reported cases of koro due to eating pork which came from a
pig that had been inoculated against swine fever. Not only did pork sales go down, but
hundreds of koro cases followed. The power of the press to cause panic was matched by
their equal power to quell the imbalance they had caused. They gave ample access to the
Singapore Medical Association and Ministry of Health who convinced the people that koro
was a result of fear, thus ending the epidemic.

further reading

books and
articles

Bartholomew, Robert E. "The Medicalization of Exotic Deviance: A
Sociological Perspective on Epidemic Koro," Transcultural Psychiatry
35(1):5-38, March 1998.